The present invention relates to footwear and, more particularly, to a footwear construction having improved shock attenuation, flexibility and energy return.
In the footwear industry, there is an ongoing effort to produce footwear having exceptional cushioning capabilities and shock attenuation. The need to produce such a cushioning system is particularly pronounced in the design of work, walking and athletic footwear, where increased cushion and rebound are primary objectives. For example, to minimize the effects of standing and walking on hard surfaces such as concrete floors, some footwear manufacturers manufacture specialty footwear that cushions the wearer's foot, particularly the heel, from the hard surface.
One example of specialty cushioning footwear is disclosed in U.S. Pat. No. 5,216,824, assigned to Wolverine World Wide, Inc. This patent discloses a walking shoe having a thick, unitary, cushioned sole having two integral protrusions in the heel and forefoot. These two protrusions are each surrounded by separate, deep grooves that isolate the respective heel and forefoot protrusions and their vertical movement relative to a peripheral ledge. This construction of the sole allows those protrusions to sink upward, into the sole a certain amount and then rebound to respectively provide some shock attenuation and toe off efficiency. While this provides cushioning and energy return to the wearer, the monolithic sole and the two protrusions sometimes can be too rigid, which impairs its ability to be laterally flexible and to provide medial to lateral, or vice versa, compression. The configuration of the two protrusions and the respective surrounding grooves sometimes can impair adequate vertical compression.
Although conventional cushioning systems can provide cushioning and energy return, there remains a long felt and unmet need for a footwear construction that provides these features as well as inherent flexibility and suppleness of the sole to enhance comfort of the footwear.